@Josan *******
When you get into Thailand you will get a stamp that allows you to stay 60 days. If you want to stay another week you visit an Immigration Office in your area and apply for an Extension of Stay, you will get 30 days extra. They not come to you to ask, if you stay 2 months and 1 week and you did not apply for this Extension of Stay, the Immigration Officer at the checkpoint where you leave will notice that you overstayed your visa and you will get fined 500 Thb a day.